x86: check for valid irq_cfg pointer in smp_irq_move_cleanup_interrupt

PATCH In review Dimitri Sivanich 1 participant 2 messages Oct 16, 2012 – Oct 24, 2012 x86

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Dimitri Sivanich

author

2012-10-16 12:50 UTC #0 lore raw

PATCH 1/1 x86: check for valid irq_cfg pointer in smp_irq_move_cleanup_interrupt

Posting this patch to fix an issue concerning sparse irq's that I raised a while back. There was discussion about adding refcounting to sparse irqs (to fix other potential race conditions), but that does not appear to have been addressed yet. This covers the only issue of this type that I've encountered in this area.

A NULL pointer dereference can occur in smp_irq_move_cleanup_interrupt() if we haven't yet setup the irq_cfg pointer in the irq_desc.irq_data.chip_data.

In create_irq_nr() there is a window where we have set vector_irq in __assign_irq_vector(), but not yet called irq_set_chip_data() to set the irq_cfg pointer.

Should an IRQ_MOVE_CLEANUP_VECTOR hit the cpu in question during this time, smp_irq_move_cleanup_interrupt() will attempt to process the aforementioned irq, but panic when accessing irq_cfg.

Only continue processing the irq if irq_cfg is non-NULL.

Signed-off-by Dimitri Sivanich <[email protected]>

---
 arch/x86/kernel/apic/io_apic.c |    3 +++
 1 file changed, 3 insertions(+)

arch/x86/kernel/apic/io_apic.c +3 -0

Index: linux/arch/x86/kernel/apic/io_apic.c
===================================================================
@@ -2257,6 +2257,9 @@ asmlinkage void smp_irq_move_cleanup_int
 			continue;
 
 		cfg = irq_cfg(irq);
+		if (!cfg)
+			continue;
+
 		raw_spin_lock(&desc->lock);
 
 		/*

tip-bot for Dimitri Sivanich

author

2012-10-24 13:00 UTC #1 lore raw

[tip:x86/urgent] x86/irq/ioapic: Check for valid irq_cfg pointer in smp_irq_move_cleanup_interrupt

Commit-ID:  94777fc51b3ad85ff9f705ddf7cdd0eb3bbad5a6
Gitweb:     http://git.kernel.org/tip/94777fc51b3ad85ff9f705ddf7cdd0eb3bbad5a6
Author:     Dimitri Sivanich <[email protected]>
AuthorDate: Tue, 16 Oct 2012 07:50:21 -0500
Committer:  Ingo Molnar <[email protected]>
CommitDate: Wed, 24 Oct 2012 12:53:51 +0200

x86/irq/ioapic: Check for valid irq_cfg pointer in smp_irq_move_cleanup_interrupt

A NULL pointer dereference can occur in smp_irq_move_cleanup_interrupt() if we haven't yet setup the irq_cfg pointer in the irq_desc.irq_data.chip_data.

In create_irq_nr() there is a window where we have set vector_irq in __assign_irq_vector(), but not yet called irq_set_chip_data() to set the irq_cfg pointer.

Should an IRQ_MOVE_CLEANUP_VECTOR hit the cpu in question during this time, smp_irq_move_cleanup_interrupt() will attempt to process the aforementioned irq, but panic when accessing irq_cfg.

Only continue processing the irq if irq_cfg is non-NULL.

Signed-off-by Dimitri Sivanich <[email protected]>

Cc Suresh Siddha <[email protected]>

Cc Joerg Roedel <[email protected]>

Cc Yinghai Lu <[email protected]>

Cc Alexander Gordeev <[email protected]>

Link http://lkml.kernel.org/r/[email protected] open here

Signed-off-by Ingo Molnar <[email protected]>

---
 arch/x86/kernel/apic/io_apic.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

arch/x86/kernel/apic/io_apic.c +3 -0

index c265593..1817fa9 100644
@@ -2257,6 +2257,9 @@ asmlinkage void smp_irq_move_cleanup_interrupt(void)
 			continue;
 
 		cfg = irq_cfg(irq);
+		if (!cfg)
+			continue;
+
 		raw_spin_lock(&desc->lock);
 
 		/*